daniel legziel wrote: > Would anyone be so kind to clear up some facts about entities? > > 1) Can an object be called consurrently? That is process the same entity > class and instance as a clone?
Logical object yes, physical object no. I.e. there may be several instances at once that map to the same object identity. If changes are made concurrently to several instances there will be transaction rollbacks of course. Also, this is only ONE possibility of how an EJB server is implemented. It is entirely possible to do it by only using one instance per primary key identity, in which case concurrent accesses are impossible. > 2)I thought that instances were individual and personalized by PKs... They are. See above. > then > how should I interpret the statement that multiple instances can represent > the same data. Exactly like that. Multiple instances can be associated with the exact same identity. The only problem with that is if multiple instances associated with the exact same identity are *updated* concurrently, in which case the rule "first come first serve" holds, i.e. only the changes of the transaction that commits first will be actually stored. The others will rollback. > Should I picture the container dressing up a directory of > all > fields with their PK and creating links on PKs when two fields are equal. I did not get that allegory... it's really very very simple... several instances, same data.. nothing strange at all really. /Rickard -- Rickard �berg Author of "Mastering RMI" Chief Architect, TheServerSide.com The Middleware Company - We Build Experts! =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff EJB-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
